Description of the Prior Art
It is known that the formation of homologs of methanol by reacting methanol with carbon monoxide and hydrogen under elevated temperature and pressure is promoted by catalysts containing cobalt and halogen compounds, particularly iodine compounds.
The additional use of ligands containing phosphorus, arsenic or antimony in the catalyst is also known. Thus, according to German Offenlegungsschrift No. 26 25 627 for example, cobalt iodide or acetate is used with tributyl phosphine and other phosphines.
Finally, homolog-forming reactions are also known in which biphosphines, biarsines and bistibines are used as catalyst ligands in the presence of cobalt and suitable halogen compounds. These are elemental iodine or bromine, covalent compounds such as, for example, methyl iodide or bromide, and also ionic compounds, such as cobalt iodide or cobalt bromide, or those of the type which are required to contain cations that are inert with respect to the hydrocarbonylation reaction, such as sodium, potassium, lithium iodides or bromides (EPA o olo 373).
The yields of the particularly valuable products, acetaldehyde and ethanol, obtained by the known processes are unsatisfactory. Accordingly, the object of the present invention is to improve the product yields hitherto achieved.